Does anybody know whether it's possible load actual patches (meaning basically waveforms in one format or another) from a PC into X5?
I have some cool patches on PC in a number of formats (I'm using Audio Compositor to render my MIDI files but would like to use some keyboard for realtime response)

You need a sampler to load "waveforms". If you go to synthzone's homepage and go to Korg you will find 1000's of new patches for the x5. Check out X5 Banks. These will not be new waveforms...just new patches, programs, and combies.